Field of the Invention
The invention relates to an antenna coil, in particular for a contactless smart card, having coil turns formed by thin conductor tracks disposed in parallel on a flexible, non-conductive carrier strip in such a way that a first end of a respective conductor track is electrically conductively connected to a second end of an adjacent conductor track, and the first end of a first conductor track and the second end of a last conductor track form coil connections.
In the case of contactless smart cards, the power for supplying the semiconductor chip and the data transmitted from and to the chip are conveyed through at least one antenna coil which is disposed on or in the smart card.
Previous concepts for producing such antenna coils envisaged winding the latter from enamel-insulated copper wire. It has also been proposed to apply the antenna coils (as planar coils) directly to the plastic body of the smart card, for example through the use of thick-film technology.
The publications "Patent Abstracts of Japan, Vol. 7, No. 33 (E-157), Feb. 9, 1983 & Japanese Patent Application No. 57186802 (KOUON DENPA), Nov. 17, 1982" and "Patent Abstracts of Japan, Vol. 9, No. 189 (E-333), Aug. 6, 1985 & Japanese Patent Application No. 60057703 (MATSUSHITA), Apr. 3, 1985" disclose antenna coils having turns formed by thin conductor tracks, which are disposed in parallel on a flexible, non-conductive carrier strip, in such a way that the first end of a respective conductor track is electrically conductively connected to the second end of a neighboring conductor track, and the first end of the first conductor track and the second end of the last conductor track form coil connections.
In that case, however, the bends of the conductor tracks are made in such a way that the conductor tracks run, before and after a bend, in planes which are oriented at an angle of about 90.degree. to one another, thereby producing a three-dimensional structure. Such an antenna coil could not be incorporated into a smart card, which must, after all, only have a thickness of less than 1 mm.